Fifo implementation for AVR 8-bit controller

avr_fifo.c

struct fifo {
    uint8_t size;           /* size of buffer in bytes */
    uint8_t read;           /* read pointer */
    uint8_t write;          /* write pointer */
    unsigned char buffer[]; /* fifo ring buffer */
};
 
/* define a FIFO type for 'size' bytes */
#define MK_FIFO(size) \
    struct fifo_ ## size {                  \
        struct fifo f;                      \
        unsigned char buffer_bytes[size];   \
    }
 
/* define a fifo (type: struct fifo *) with name 'name' for 's' bytes */
#define DEFINE_FIFO(name, s)                                \
    struct fifo_##s _raw_##name = { .f = { .size = s } };   \
    struct fifo *name = &_raw_##name.f;


uint8_t FifoDataLength (struct fifo *fifo)
{
    // return length of valid data in fifo
    return (fifo->write - fifo->read) & (fifo->size - 1);
};


uint8_t FifoWrite (struct fifo *fifo, unsigned char data) 
{
    // fifo full : error
    if (FifoDataLength(fifo) == (fifo->size - 1))
    {
        return 1;
    }
    // write data & increment write pointer
    fifo->buffer[fifo->write] = data;
    fifo->write = (fifo->write + 1) & (fifo->size - 1);
    return 0;
};


uint8_t FifoRead (struct fifo *fifo, unsigned char *data)
{
    // fifo empty : error
    if (FifoDataLength(fifo) == 0)
    {
        return 1;
    }
    // read data & increment read pointer
    *data = fifo->buffer[fifo->read];
    fifo->read = (fifo->read + 1) & (fifo->size - 1);
    return 0;
};